THE EFFECTS UPON DEA EFFICIENCY OF DMUs DUE TO THE CHANGE OF NUMBER OF DMU's

The change of DEA efficiency due to increasing (or decreasing) DMU by one is studied. Here, we fully take advantage of the information obtained from evaluating the efficiency of original n DMU's, from which we derive the sufficient condition and necessary condition respectively for the change of efficiency of DMUs after the number of DMUs is changed. Particularly the necessary and sufficient condition for keeping the original situation of efficiency of DMUs unchanged are also established.